Pretty well all nuts and bolts on our Morris Minor are Whitworth, I did have a complete set of Whitworth spanners/sockets etc., but my bloody kids biffed them in the river because they reckoned they didn't fit anything and were therefore useless. (Yeah...they're still alive...just. I think She Who Must Be Obeyed would've been a wee bit upset if I'd killed them.)
But over the years I've managed to accumulate another complete set from second-hand shops and the like.
They're pretty rare; just about made of unobtainium.
And the kids now know better than to biff them.